Vacuum-processed perovskite solar cells reach 20.59% efficiency using EDAI2/4MeO-PEAI bilayer passivation

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Researchers from Korea's Jeonbuk National University have developed a rational bilayer surface passivation strategy to address one of the key bottlenecks in vacuum-deposited perovskite solar cells (PSCs): defect-rich, non-uniform crystallization arising from solid-state film formation. Schematic diagram of device structure. Image from: Advanced Functional Materials Vacuum thermal evaporation is widely regarded as a scalable route for PSC fabrication, offering precise control over thickness, stoichiometry, and large-area uniformity. However, the absence of a solvent limits mass transport and surface diffusion during film growth, often leading to incomplete crystallization and a high density of surface and grain-boundary defects. In particular, halide vacancies generate uncoordinated Pb 2+ sites, which act as nonradiative recombination centers, suppress quasi-Fermi level splitting and reduce the achievable open-circuit voltage (V OC ). These defect sites also accelerate ion migration and environmental degradation, undermining device stability. To overcome these limitations, the researchers introduced an “Anchor-and-Seal” bilayer passivation approach based on sequential deposition of ethylenediammonium diiodide (EDAI 2 ) and 4-methoxy-phenethylammonium iodide (4MeO-PEAI).